Qhy 10 image problem.

[simmo39]

Had a try last night with my qhy 10, This was only a test but on processing in PI I  found these  dotted lines. Any ideas on what they are and how to get rid?

The camera was cooled to - 15 at the time, do i need to be cooler? 

Many thanks.

[pete_l]

Quote

do i need to be cooler? 

We could probably all do with being a little cooler. Have you tried a leather jacket?

But those dots look to me like hot pixels, that change position due to the stacking of your subframes.

[simmo39]

1 minute ago, pete_l said:

We could probably all do with being a little cooler. Have you tried a leather jacket?

But those dots look to me like hot pixels, that change position due to the stacking of your subframes.

Im wrapped up ok.lol , thats what i thought but when i had this problem with my DLSR stacking in PI seemed to reduce them. Not sure if im doing something wrong in PI.

[pete_l]

it looks like there are 5 dots each time. 5 subs. perchance. Does it just need a master dark frame to be subtracted from each one before you stack them?

[simmo39]

13 minutes ago, pete_l said:

it looks like there are 5 dots each time. 5 subs. perchance. Does it just need a master dark frame to be subtracted from each one before you stack them?

Yep 5 subs but i did use a master dark and bias. The only thing i can think of is i got a setting wrong on PI.

[Zakalwe]

Those are hot pixels. The drift between the frames means they appear to "walk" in the image. Change your stacking algorithm to a Kappa Sigma (you'll need more frames- 15 or 16 from memory) and the algorithm will reject them as outliers in the data.

 

[LightBucket]

What Zakalwe said..

[simmo39]

Thanks guys, done a quick re do and a lot better.

[Astrobug]

Some dithering would help also.